Hi,

Our ISP upgraded our cablemodem to a Cisco DPC3000 to support higher internet speed. I replaced our old modem with the new one and now I get no DHCP leases in my mikrotik rb750gl. If I connect a laptop and configure the ethernet por for DHCP, it works without a flaw. However, the mikrotik router gets stalled in the "searchig..." state.

It is interesting to note that during the startup of the modem, the mikrotik router gets a lease for IP address 192.168.100.20, which is lost 20 seconds after.

I've tried several ethernet port parameters (with/without autonegotiation, with/without full duplex, 10,100,1000). If I leave it in the default setup, I get 1 Gbps FD autonegotiated.

BTW, I can look the traffic in the interface using torch, and I see 10kbps of incoming traffic of bootpc and bootps protocols.

Any clue?

It sounds like the modem has locked on to your mac address of your computer. You could call the ISP and have the flush the ARP on the modem or copy the mac address from your computer to the ether port on your router connected to your modem.

That was my first impression. I used a second laptop to be sure that it wasn't a MAC issue, and the second laptop worked without a flaw. I power cicle the modem after I change the device connected to it, to make it flush the arp cache.

Post /export compact

# jan/02/1970 01:06:38 by RouterOS 5.21
# software id = PWE8-V4YI
#
/interface ethernet
set 0 name=ether1-gateway
set 1 name=ether2-master-local
set 2 master-port=ether2-master-local name=ether3-slave-local
set 3 master-port=ether2-master-local name=ether4-slave-local
set 4 master-port=ether2-master-local name=ether5-slave-local
/interface pptp-server
add name=pptp-in1 user=user1
/ip hotspot user profile
set [ find default=yes ] idle-timeout=none keepalive-timeout=2m
/ip pool
add name=default-dhcp ranges=192.168.88.10-192.168.88.254
/ip dhcp-server
add address-pool=default-dhcp interface=ether2-master-local name=default
/interface pptp-server server
set enabled=yes
/ip address
add address=10.176.69.31/24 comment="LAN 2" interface=\
ether2-master-local
add address=192.168.0.254/24 comment="LAN 1" interface=\
ether2-master-local
/ip dhcp-client
add default-route-distance=0 disabled=no interface=ether1-gateway
/ip dhcp-server network
add address=192.168.88.0/24 comment="default configuration" dns-server=\
192.168.88.1 gateway=192.168.88.1
/ip dns
set allow-remote-requests=yes max-udp-packet-size=512 servers=\
192.168.0.1,212.160.234.73
/ip dns static
add address=192.168.88.1 name=router
/ip firewall filter
add chain=input comment="default configuration" protocol=icmp
add chain=input comment="default configuration" connection-state=established
add chain=input comment="default configuration" connection-state=related
add chain=input dst-port=80 protocol=tcp
add chain=input dst-port=1723 protocol=tcp
add chain=input protocol=gre
add action=drop chain=input comment="default configuration" in-interface=\
ether1-gateway
/ip firewall nat
add action=masquerade chain=srcnat comment="default configuration" \
out-interface=ether1-gateway to-addresses=0.0.0.0
/ip neighbor discovery
set ether1-gateway disabled=yes
/ppp secret
add comment="User1" local-address=172.16.1.1 name=\
user1 password=Ilovepasswords profile=default-encryption remote-address=\
172.16.1.2 routes="10.176.101.0/24 172.16.1.2 1" service=pptp
add disabled=yes local-address=172.16.1.3 name=user2 password=test profile=\
default-encryption remote-address=172.16.1.4
/system clock
set time-zone-name=Europe/Madrid
/system identity
set name=MyRouter
/system ntp client
set enabled=yes mode=unicast primary-ntp=176.31.173.182 secondary-ntp=\
93.92.239.129
/tool mac-server
add disabled=no interface=ether2-master-local
add disabled=no interface=ether3-slave-local
add disabled=no interface=ether4-slave-local
add disabled=no interface=ether5-slave-local
/tool mac-server mac-winbox
set [ find default=yes ] disabled=yes
add interface=ether2-master-local
add interface=ether3-slave-local
add interface=ether4-slave-local
add interface=ether5-slave-local

Everything looks fine to me. Try cloning your mac from one of the pcs and see if it works.

Got it! The MAC address was the key. We have a fixed IP address and the provider messed the configuration when changing the cablemodem. It was working with all the MACs except our own's

I changed the MAC address (substituted the last digit) and I got a dynamic IP.

Thanks very much for your kind help. Next time I'll blame my ISP before posting

Regards

Next time I'll blame my ISP before posting